Observation and diagnosis of an internal lumen by an electronic endoscope is a diagnosis method widely used at present. Since this diagnosis method directly observes the internal tissue, there is an advantage that there is no need to cut a lesion portion, and the burden on a subject is small. On the other hand, such method which directly observes the internal lumen is considered to have lower certainty and accuracy compared to a pathological examination after a biopsy. Therefore, continuous effort is made to enhance quality of imaging.
Lately, other than a so-called videoscope, diagnosis devices which use various optical principles and ultrasonic diagnosis devices are proposed, and some are in practical use. In these areas, in order to improve the diagnosis certainty, new measuring principles are introduced, or a plurality of measuring principles are combined.
Specifically, it is known that information which cannot be obtained by simply looking at the image of the tissue can be obtained by observing and measuring fluorescence from the tissue and the fluorescence from the fluorescent material applied to the tissue. A fluorescent image endoscope system is proposed to obtain the fluorescent image, to overlap the fluorescent image to the normal visual image and to display the image. Such system is highly desired, because it is possible to discover a malignant tumor at an early stage.
Moreover, there is also known a method to judge a state of tissue by obtaining intensity information of fluorescence without configuring the fluorescent image. In such method, fluorescence is obtained without using the imaging element mounted in the electronic endoscope.
As a diagnosis tool for fluorescent diagnosis, in other words, probe, there are those which enter the body through a forceps channel of an endoscope, or those which are formed as one with the endoscope. The fluorescence observation probe described in Patent Document 1 and Patent Document 2 enter the body by inserting the probe in the forceps channel of the endoscope.